Quarterly report pursuant to Section 13 or 15(d)

Note 6 - Stockholders' Equity (Details Textual)

v3.22.2.2
Note 6 - Stockholders' Equity (Details Textual) - USD ($)
1 Months Ended 3 Months Ended 6 Months Ended
Mar. 25, 2022
Mar. 31, 2021
Feb. 28, 2021
Jan. 31, 2021
Jun. 30, 2022
Jun. 30, 2022
Jun. 30, 2021
Sep. 03, 2021
Proceeds From Issuance of Common Stock, Net of Issuance Costs           $ 8,000 $ 33,399,000  
Common Stock, Maximum Amount to Be Distributed Through Financial Institutions               $ 75,000,000
January 2021 Offering [Member]                
Stock Issued During Period, Shares, New Issues (in shares)       3,076,924        
Shares Issued, Price Per Share (in dollars per share)       $ 2.60        
Proceeds From Issuance of Common Stock, Net of Issuance Costs       $ 8,000,000.0        
Payments of Stock Issuance Costs       $ 73,000        
February 2021 Offering [Member]                
Stock Issued During Period, Shares, New Issues (in shares)     2,926,830          
Shares Issued, Price Per Share (in dollars per share)     $ 4.10          
Proceeds From Issuance of Common Stock, Net of Issuance Costs     $ 12,000,000.0          
Payments of Stock Issuance Costs     $ 70,000          
March 2021 Offering [Member]                
Stock Issued During Period, Shares, New Issues (in shares)   1,512,499            
Shares Issued, Price Per Share (in dollars per share)   $ 9.00            
Proceeds From Issuance of Common Stock, Net of Issuance Costs   $ 13,600,000            
Payments of Stock Issuance Costs   $ 72,000            
Tumim [Member]                
Common Stock, Maximum Shares Sold (in shares) 10,000,000              
Tumim [Member] | Purchase Agreement [Member]                
Stock Issued During Period, Shares, New Issues (in shares) 50,000         7,425    
Stock Issued During Period, Value, New Issues $ 100,000              
Shares Issued, Price Per Share (in dollars per share)         $ 1.11 $ 1.11    
Proceeds From Issuance of Common Stock, Net of Issuance Costs           $ 8,000    
Common Stock, Maximum Shares Allowed to Issue and Sell, Initial (in shares) 7,361,833              
Common Stock, Maximum Shares Allowed to Issue and Sell, Percentage of Shares Issued and Outstanding, Initial 19.99%              
Common Stock, Price Per Share, Percentage of Weighted Average Price 95.00%              
Tumim [Member] | Purchase Agreement [Member] | Minimum [Member]                
Beneficial Ownership, Minimum Percentage of Shares Outstanding, Initial 4.99%              
Tumim [Member] | Purchase Agreement [Member] | Maximum [Member]                
Beneficial Ownership, Minimum Percentage of Shares Outstanding, Initial 9.99%              
Agents [Member] | Sales Agreement [Member]                
Proceeds From Issuance of Common Stock, Net of Issuance Costs         $ 24,000 $ 24,000    
Common Stock, Maximum Amount to Be Distributed Through Financial Institutions               $ 75,000,000
Financial Institutions, Commission Rate               3.00%